SpoIVFB Site-2 protease (S2P), a zinc metalloprotease (MEROPS family M50B), regulates intramembrane proteolysis (RIP), and is involved in the pro-sigmaK pathway of bacterial spore formation. SpoIVFB (sporulation protein, stage IV cell wall formation, F locus, promoter-distal B) is one of 4 proteins involved in endospore formation; the others are SpoIVFA (sporulation protein, stage IV cell wall formation, F locus, promoter-proximal A), BofA (bypass-of-forespore A), and SpoIVB (sporulation protein, stage IV cell wall formation, B locus). SpoIVFB is negatively regulated by SpoIVFA and BofA and activated by SpoIVB. It is thought that SpoIVFB, SpoIVFA, and BofA are located in the mother-cell membrane that surrounds the forespore and that SpoIVB is secreted from the forespore into the space between the two where it activates SpoIVFB.
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